numpy min 和 max 函数返回 nan

Question

我有一个充满浮点数的二维数组，表示其他两个二维数组之间的差异。我需要创建一个等高线并对其进行映射，但是当我尝试绘制等高线时，我收到一条错误消息，指出我的等高线至少需要 2 个级别。

ValueError：填充轮廓需要至少 2 个级别。 错误开始于 a = np.min(tsEndAvg) 和 b = np.max(tsEndAvg)

 k = int(raw_input("Enter the iteration amount: "))*12
    x = 0
    # Appending Arrays to cover last 360th slot of lon
    lon2 = np.empty(len(lon)+1)
    for l in range(0, len(lon)):
        lon2[l] = lon[l]
    lon2[len(lon2) - 1] = 360.
    # Creating temp arrays for manipulation later
    tssum = np.empty([len(lat), len(lon)+1])
    tsEndSum = np.empty([len(lat), len(lon) + 1])
    ts2 = np.empty([len(lat), len(lon2)])
    time2 = np.empty(len(time))
    tsEndAvg = np.empty([len(lat), len(lon) + 1])

#START WHILE FOR BEGINNING DATA
    while x < k:
        print str(x)
        # x iterates through a slice of time, k is the iteration amount
        # Attempting to grab global sum of surface temperatures over k iterations
        ts = tempts[x, :, :]
        for i in range(0, len(lat)):
            for j in range(0, len(lon)):
                ts2[i][j] = ts[i][j]
        for i in range(0, 192):
            ts2[i][len(lon2) - 1] = ts[i][0]

        tssum = tssum + ts2# Running sum of the global data
        newDate = beginDate + datetime.timedelta(time[x])
        print newDate
        x = x + 1
    # Dividing each data point in tssum by k for the average amount
#END WHILE
    tssum = tssum / k

#START WHILE FOR END DATA
    x = len(time) -1
    while x > (len(time) - 1) - k:
        # x iterates through a slice of time, k is the iteration amount
        # Attempting to grab global sum of surface temperatures over k iterations
        print x
        ts = tempts[x, :, :]
        for i in range(0, len(lat)):
            for j in range(0, len(lon)):
                ts2[i][j] = ts[i][j]
        for i in range(0, 192):
            ts2[i][len(lon2) - 1] = ts[i][0]
        tsEndSum = tsEndSum + ts2
        x = x - 1
#END WHILE

# AVERAGING ALL GLOBAL DATA
    tsEndSum = tsEndSum / k
    tsEndAvg = tsEndSum - tssum
#END AVG   
    a = np.min(tsEndAvg)
    b = np.max(tsEndAvg)

    plt.figure()
    ax = plt.axes(projection=c.PlateCarree())
    ax.coastlines(resolution='50m', linewidth=.25)
    ax.outline_patch.set_visible(False)
    lon2, lat2 = np.meshgrid(lon2, lat)
    plt.contourf(lon2, lat2, tsEndAvg, levels=np.arange(a,b,1)) #ERROR POINTS TO THIS LINE
    name = "SurfaceTempAnom-"+str(k/12)+".png"
    plt.savefig("/Users/Robert/PycharmProjects/CESM/anoms/"+name, dpi=750, bbox_inches='tight', pad_inches=0)
    print('saved: '+name)

Answer 1

好吧，请向我们展示您的输入数据，因为它应该可以工作。例如，请参阅最小示例：

将 numpy 导入为 np a=[[1,2],[3,4]] 打印 np.max(a)

它将返回 4。因此最可能的问题是：

• 输入不能被解释为 np 数组
• 它不是浮点数列表/数组
• ...